Having to change a blown rear air bag. I have never performed a repair as this, any advice out there for the correct way to block up the bus etc? Im mechanically inclined but the size and weight seem to be a little intimidating. Any advice or photos will be greatly appreciated.

Please help us help you! Take a few minutes to edit your profile to include a signature line - similar to mine below - that includes at least your first name, home base city/state, and make/model of your coach.

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What is the VIN on your coach? PD4106-XXXX?

Do you have the maintenance manual & it's supplement? There's a wealth of information in both, including air bag replacement procedures. The parts book also has a bunch of exploded drawings to help you, too. And an Operator's Manual will often answer "what is this for?" All four should be in your library, five if you include a DD 8V71 manual.

If you don't have it already, memorize this number: 1-888-262-2434. That's Luke @ US Coach in NJ. He's probably forgotten more about GMC buses than all the combined knowledge on the major bus bulletin boards. Strong supporter of our crazy hobby, knows the correct parts for the applications, reasonable prices and ships same day when you use plastic money. Support those who support us!

Working on a 4106 is not much worse than working on a GM car, only bigger.

Crib blocking of the coach body is much safer than using jack stands. Block on the main bulkheads on either side of the axles. A 20-ton air over hydraulic jack is extremely helpful.

Check the leveling valves also - you may have a bad one, not a bad air bellow.

RJ is right of course that it my not be the air bellows. It could also be a rusted can inside the air bellows. I had that on our 4106 twice and on the Prevost I had once. What are commonly called "leveling valves" are really height control valves, although the parts person will know what you are talking about either way. Your parts manual will refer to them as height control valves. That may save you some time looking for them.

Changing the air bag is not hard, but takes a little time since there are a bunch of bolts. The biggest issue is jacking and blocking the bus to it is safe to be under it. When that is done, let the air out of the suspension so the bags hang fully extended. You will then have lots of room to remove and replace them. Are your bags plated? If so, they take a longer bolt. Luke recommends using all new bolts. They have special heads, so don't try any hardware store stuff. I have found the bicycle tire tools work well to remove and replace the air bag ring.

Anyway, make sure that you have the problem diagnosed correctly before removing the bags. See if air is leaking from somewhere else. Since you describe the bag as blown, it would seem you know where the hole is.

Lin, air bellows do not mount the same on a 4106 as they do on an MCI. No special bolts are needed nor are any block off plates, since GM 4106's don't have air beams. They have rolling lobe type air bellows. Just an FYI.